[commit] r2491 - cpu/arm

[repository service]

Author: wmb
Date: Wed Aug 31 10:21:10 2011
New Revision: 2491
URL: http://tracker.coreboot.org/trac/openfirmware/changeset/2491

Log:
ARM - Added some comments to ARM multiplication code words.  No functional change.

Modified:
   cpu/arm/muldiv.fth

Modified: cpu/arm/muldiv.fth
==============================================================================
--- cpu/arm/muldiv.fth	Wed Aug 31 10:19:47 2011	(r2490)
+++ cpu/arm/muldiv.fth	Wed Aug 31 10:21:10 2011	(r2491)
@@ -208,23 +208,23 @@
 c;

code fm/mod  ( d.dividend s.divisor -- s.rem s.quot )
-   mov     r3,tos
-   mov     r2,tos,asr #0		\ sign extend divisor
-   pop     r0,sp
-   pop     r1,sp
-   stmdb   sp!,{r8,r9}
+   mov     r3,tos           \ r3:divisor.low
+   mov     r2,tos,asr #0    \ r2:divisor.high (sign extended)
+   pop     r0,sp            \ r0:dividend.high
+   pop     r1,sp            \ r1:dividend.low
+   stmdb   sp!,{r8,r9}      \ save r8 and r9
    cmp     r0,#0
-   < if
+   < if                     \ negative dividend?
       rsbs    r1,r1,#0
-      rsc     r0,r0,#0
+      rsc     r0,r0,#0      \ r0,r1: abs(dividend)
       cmp     r2,#0
-      < if
+      < if                  \ negative divisor?
          rsbs    r3,r3,#0
-         rsc     r2,r2,#0
+         rsc     r2,r2,#0   \ r2,r3: abs(divisor)
          bl      'code (u64division)
          rsbs    r1,r1,#0
-         rsc     r0,r0,#0
-      else
+         rsc     r0,r0,#0   \ negate remainder for floored division
+      else                  \ nonnegative divisor
          mov     r8,r2
          mov     r9,r3
          bl      'code (u64division)